This project is an investigation of the mechanism of bone and tooth mineralization and, more specifically, a study of the role of phospholipids and phospholipid complexes in the initiation of biological calcification. X-ray diffraction, infrared spectroscopy and electron microscopic studies will be made on synthetic Ca-phospholipid-PO4 complexes to characterize their structure and properties. Kinetic studies will be done on the formation of hydroxyapatite in the presence of such complexes. Attempts will be made to isolate such complexes from mineralizing hard tissue. A study will be made on the variation of phospholipid concentration and type in the mineralization of teeth and bone.